The present invention relates to a method comprising the steps of coating and drying photoreceptor base drums used for electrophotography which are vertically conveyed under the condition that they are longitudinally connected, and also relates to a method comprising the step of successively separating the photoreceptor drums which have been coated.
When the surfaces of photoreceptor base drums are continuously coated and dried under the condition that the base drums are stacked and the end faces are butted, the stacked base drums are connected with each other by the dry coating films, so that the base drums can not be easily separated.
Although a means is provided for separating the base drums immediately after the coating operation has been completed, it is not appropriate to apply the means to a case where the coating solution is of a quick drying type, and also it is not appropriate to apply the means to a case where the coated base drums are sent into a drier for stopping the flow of the coating solution on the drum surfaces.
Japanese Patent Publication Open to Public Inspection Nos. 120662/1986, 120663/1986 and 120664/1986 disclose technique in which the coating and separating operation is performed under the condition the base drums are stacked through spacers. However, when vibration is caused by the separating means, the vibration is transmitted to the base drums which are being continuously coated. As a result, deviation of coated film thickness is increased.
Since the coating solution flows down on the base drum surface immediately after it has been coated, it is preferable that the base drum coated with the photoreceptor coating solution is quickly put into the drying process immediately after the completion of coating operation.
In the case where the base drums have been connected with each other by the dry coating film, a means is used, in which one base drum is pulled upward when the conveying speed of the base drum is increased. However, this method is disadvantageous in that the adjacent drums are also pulled upward.
There is provided a method in which the base drum to be separated is vibrated, and also provided a method in which the base drum to be separated is seized with a chuck to change the axial direction of the base drum. According to these methods, deviation is caused in the coating film thickness, and further the base drums collapse due to the vibration, so that the manufacture can not be stably carried out.
According to the method in which the coating film is quickly dried with a drier immediately after the coating operation has been completed, advantageous effects can be provided with respect to the coating film. However, even when the base drum is dried with the drier, in some cases, the coating film can not be sufficiently dried depending on the characteristics of the coating solution and the film thickness to be obtained. In the case where the coating film has not reached a condition of set to touch, the base drum can not be directly held. Therefore, it is difficult to separate and recover the base drum.
The present invention has been achieved to solve the above problems. The first object of the present invention is to stably separate and recover a coated photoreceptor drum even when continuously coated base drums are stacked according to the continuous coating method, without causing vibration and slippage of the base drum position.
Also, the present invention relates to a drier for drying the photoreceptor for electrophotographic use after the photosensitive layer has been coated.
Conventionally, there are provided two types of driers for drying the photosensitive layer immediately after the completion of coating. One is a type of drier in which air is directly blown against the base drum immediately after the coating operation has been completed. This type of drier is disclosed in Japanese Patent Publication Open to Public Inspection Nos. 73074/1984 and 4471/1987. The other is a type of drier in which sucked air is used for drying the photosensitive layer, wherein a draft is used as disclosed in Japanese Patent Publication No. 4470/1987.
The drier disclosed in Japanese Patent Publication Open to Public Inspection Nos. 73074/1984 and 4471/1987 in which air is blown to the coating film, is disadvantageous in that the coating film is damaged or the coating film thickness deviates since the air flow collides with the coating film.
The drier disclosed in Japanese Patent Publication Open to Public Inspection No. 4470/1987 in which sucked air is used for drying the coating film, is disadvantageous in that the coating film thickness deviates due to the turbulence caused in the draft. Therefore, the coating film thickness tends to deviate.
According to the aforementioned methods, the lower the viscosity of the coating solution is, the more the coating film thickness deviates. Also, time from the completion of coating to the start of drying is an important factor. After the coating film has been naturally dried for a predetermined period of time, the aforementioned method can be applied. However, the aforementioned methods are not appropriate when they are applied immediately after the completion of coating operation.
According to the present invention, the problems described above can be solved. It is the second object of the present invention to evaporate the coating solvent uniformly and quickly without affecting the coating film immediately after the completion of coating. Further, it is the second object of the present invention to provide a drier in which the occurrence of turbulence is suppressed in the region close to the coating film surface to be dried and solvent vapor staying along the coating film is removed so as to complete a uniform and stable photosensitive layer.